Conventionally, it has been attempted or proposed that an adjustable lumbar support, thigh support, side support or the like be installed in a automotive vehicle seat, particularly driver's seat, to adjust seating position of the seat. In U.S. Pat. No. 3,330,598 issued on July 11, 1967, to George Harold Whiteside, there is shown a seat whose seat cushion and seat back are composed of a plurality of pneumatic chambers and each pneumatic chamber is connected to a pressurized gas supply source through a pressure control means. Further, Japanese Patent Application for Utility Model Publication No. Sho. 47-11021, published on Oct. 9, 1971 shows a seat for automotive vehicle equipped with a pneumatic lumbar support for which the tension of the portion thereof in contact with the lumbar region of the seated passenger is adjusted by adjusting the pressure of working gas in the pneumatic chamber.
In the above seat, a pneumatic pump is used as a pressure gas supply source, and this pump is installed in the vehicle compartment. Accordingly, such conventional devices may cause problems in that the vehicle body weight will be increased owing to this pneumatic pump and in addition, the manufacturing cost will also be increased. Additionally, since the pneumatic pump is ordinarily arranged in the vehicle compartment, space for mounting the pump is required. Furthermore, working noise is generated in the compartment since the pump is arranged in the compartment, thereby disturbing the quietness of the compartment.
Therefore, it is the primary object of the present invention to provide an adjusting device for a seat which has improved operational capabilities without a dedicated pneumatic pump, and can work without degrading the quietness of the vehicle compartment.